select 
    t1.level,
    count(t1.uid) as level_cnt
from 
    user_info t1,
    examination_info t2,
    exam_record t3
where
    t1.uid = t3.uid
    and t2.exam_id = t3.exam_id
    and t2.tag = 'SQL'
    and t3.score > 80
group by
    t1.level
order by
    level_cnt desc